'Visibility will drop to near zero' in parts of New York state getting hammered with lake-effect snow

Parts of New York state are getting walloped Thursday by a snowstorm that could shut down roads and paralyze cities for days.

"This event will have the very real potential to produce a paralyzing snowfall that could be measured in feet for the Buffalo and Watertown metro areas," the National Weather Service in Buffalo said.

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The ferocious snowstorm started Wednesday and is expected to cause treacherous road conditions at least through the end of the week.

"Visibility will drop to near zero at times and roadways will be covered with snow making travel hazardous to nearly impossible," the National Weather Service said.

The storm by Wednesday night had already dumped 10 inches of snow on South Wales, about 25 miles southeast of Buffalo. The nearby town of Colden got hit with more than 8 inches of snow, the weather service said.

And the worst is yet to come.

The heaviest snow is expected to start Thursday evening and last through Friday, with more bouts of intense snow over the weekend, the weather service said.

"This is going to be a very long-lasting and major lake-effect snow event east of Lake Erie and Lake Ontario," National Weather Service meteorologist Jon Hitchcock told CNN.

Areas downwind of lakes Erie and Ontario could get hit with thunder and lightning on top of the snowfall.

Several feet of snow also are forecast Thursday and Friday for the Buffalo and Watertown areas of New York and northwest Pennsylvania, the National Weather Service said.

The snow could fall at a rate of 3 inches per hour in some places, with snow piling up to 4 feet in some areas.

LAKE-EFFECT SNOW PUMMELS OTHER STATES, TOO

Some parts of Indiana and northeast Ohio have already picked up more than a foot of snow, CNN Meteorologist Dave Hennen said.

And more than 5 million people around the Great Lakes are under snow alerts Thursday.

The areas are getting hammered with lake-effect snow -- which happens when very cold, windy conditions form over a not-so-cold lake.

A lake, for example, might be about 40 degrees, while the air temperature could be well below freezing.

"That differential in temperatures creates some instability and the water provides a moisture source," CNN Meteorologist Brandon Miller said. "When it gets over land, it deposits water vapor as snow."

'DO NOT UNDERESTIMATE THIS STORM'

Commercial traffic will be banned starting at 4 p.m. Thursday on about 130 miles of the New York State Thruway (Interstate 90) in the Rochester and Buffalo area to the Pennsylvania border, Gov. Kathy Hochul's office said.

Residents should take precautions -- and care of one another, the state's head of emergency services urged.

"Do not underestimate this storm," said Jackie Bray, commissioner for New York state's Division of Homeland Security and Emergency Services.

"We should all check on our neighbors, particularly vulnerable neighbors, to help them prepare for winter weather in the forecast."

STATE OF EMERGENCY EXPECTED

New York's governor plans to issue a state of emergency Thursday, she said.

"My team and I are deploying emergency response assets ahead of the storm, remain in constant contact with local officials, and are laser focused on the forecast," Hochul said in a news release.

"New Yorkers should remain vigilant ahead of the storm and avoid any unnecessary travel during these hazardous conditions."